The source of immigration is not rooted in the individual initiatives of those who come here. There is a strong movement in the world to do away with the sovereignty of individual countries. Notice that immigrants are herded towards the countries which have the greatest number of independently minded citizens. To remove sovereignty from the United States it is helpful to have a huge influx of citizens who share no common cultural values or nationalist feelings with traditional Americans.
The other incentive is to draw in foreigners is simply to pack in low cost labor and replace the spending power of low income Americans who have been fleeced by central economic planning. Collectively, the poor have a great deal of spending power.
Notice from the chart above, there has been no job growth over the past decade. Poverty is better here than it is in other places but new arrivals are not accepting our surplus jobs because there aren’t any. Open borders are fine in a world where free markets are flourishing. The world has no free markets so the flow of humans back and forth between nations is determined by political considerations.
The United States has no politicians who are anti-immigrant. There are those who insist the current immigration laws be enforced. Others want us all to close our eyes and just not enforce laws. The benefits of having many new citizens goes to the elite who constantly lobby to draw them in.